1. Field of the Invention
The present invention relates to the preparation of purified barium-based compounds, and, more especially, to the preparation of a purified barium salt, in particular having a low strontium content. The process of the invention is particularly advantageous for the production of barium carbonate in a high degree of purity, which carbonate is a convenient precursor for a barium titanate having the same degree of purity.
2. Description of the Prior Art
The demand for high-purity barium salts is increasing, for example, for use in barium titanate-based ceramic capacitors or barium hexaferrite-based magnetic discs.
However, barium-based ores, whether comprising, e.g., sulfate, as in barytes, or carbonate, as in the case of withesite, contain many impurities, in particular iron, calcium, sodium and strontium. Other impurities such as chlorine or sulfur may also be introduced over the course of the conventional processes for the production of barium carbonate.
And while most of the aforenoted impurities typically accompanying barium may be removed relatively easily by conventional precipitation/redissolution processes, the removal of trace amounts of strontium remains an acute problem due to the high degree of similarity between the chemical properties of these two elements.
Even given the fact that processes for the separation of strontium and barium are known to this art, for example, based on chromatography or on ion exchange procedures, these are only laboratory-scale procedures which permit quantitative determination of the strontium, rather than true separation processes which can be carried out technically or economically on an industrial scale.